Background: Prediction of the course of multiple sclerosis (MS) was traditionally based on features close to onset.Objective: To evaluate predictors of the individual risk of secondary progression (SP) identified at any time during relapsing-remitting MS.Methods: We analysed a database comprising an untreated MS incidence cohort (n=306) with five decades of follow-up. Data regarding predictors of all attacks (n=749) and demographics from patients (n=157) with at least one distinct second attack were included.Results:The average hazard function of transition to SPMS was 0.046 events per patient year, showing a maximum at age 33. Three elements were significant predictors: age, a descriptor of the most recent relapse, and the interaction between the descriptor and time since the relapse. A hazard function termed “prediction score” estimated the risk of SP as number of transition events per patient year (range <0.01 to >0.15).Conclusions: The insights gained from this study are that the risk of transition to SP varies over time in individual patients, that the risk of SP is linked to previous relapses, that predictors in the later stages of the course are more effective than the traditional onset predictors, and that the number of potential predictors can be reduced to a few (three in this study) essential items. This advanced simplification facilitates adaption of the “prediction score” to other (more recent, benign or treated) materials, and allows for compact web-based applications (http://msprediction.com).

The MS Prediction Score estimates the current risk of transition to the secondary progressive phase in patients with relapsing-remitting multiple sclerosis.

It is expressed as a percentage indicating the yearly risk of such transition at the present time.The calculator uses the time difference between the last attack and the present day.

The consensus definition of secondary progression is as follows: Initial relapsing-remitting disease course followed by progression with or without occasional relapses, minor remissions and plateaus. We refer to insidious progression as a disease course that usually leads to considerable disability.